David Norgrove told the BBC a rising life expectancy meant millions of people would “undoubtedly” have to wait longer in future to draw a state pension.

The state pension age is set to rise to 66 in 2024, 67 in 2034 and 68 in 2044.

Norgrove said: “People are going to have to work longer, partly because as a nation we’re not going to save as much for retirement as we did in the past.

“The government’s recent legislation is increasing the state retirement age progressively to 68. I think it will end up higher than that.”

He added the ability of the current working generation to pay for the retirement of its predecessor would be “a real issue for the next 30 years”.

However, pensions minister Angela Eagle has said there was “no point” raising the state retirement age beyond 68.

She said: “We believe that we’ve covered the predictions of increased life expectancy adequately in the legislation and unless these statistics change we’ll have periodic reviews, but it won’t happen for another generation.”